FIG. 1 is a schematic diagram of an architecture of a network for performing location registration by a user equipment (UE, User Equipment).
The network architecture includes a home subscriber server/home location register (HSS/HLR, Home Subscriber Server/Home Location Register), a mobility management node (MMN, Mobility Management Node), a mobile switching center/visit location register (MSC/VLR, Mobile Switching Center/Visit Location Register), and a UE.
The HSS/HLR mainly includes subscriber subscription information and location information; the MMN may be a serving GPRS support node (SGSN, Serving GPRS Support Node) of a serving GERAN/UTRAN network or a mobility management entity (MME, Mobility Management Entity) of a serving LTE network; the MSC/VLR mainly provides a circuit domain service and location management.
When the UE moves between a 2G/3G system and an LTE system, the UE performs location registration by using a process of a routing area update (RAU, Routing Area Update), or location area update (LAU, Location Area Update), or tracking area update (TAU, Tracking Area Update). For a short message service (SMS, Short Message Service), when a short message of the UE needs to be delivered, a short message center obtains address information of a node serving the UE by means of a query from the HSS. The HSS/HLR needs to return a correct address of the serving node according to registration information of the UE in the MSC/VLR, SGSN, or MME. The short message center forwards the short message to the corresponding serving node after receiving the address of the node serving the UE, and the serving node sends the short message to the UE.
With continuous development of wireless network communications, at present, an emerging communication manner, namely machine type communication (MTC, Machine Type Communication), is gradually popularized. The MTC means network communication performed between one or more nodes or devices without human intervention, and a user equipment in such a communication mode is called a machine to machine (M2M, Machine to Machine) user equipment.
In an MTC system, some M2M user equipments do not need circuit domain voice services, and all services (including short messages) thereof may be obtained from a packet domain. To prevent an impact on performance of the MSC from excessive M2M user equipments, the 3GPP specifies that the MME/SGSN may enhance a short message function of the MSC and provide a short message service for a user, thereby reducing a load of processing the short message by the MSC.
In the prior art, when the M2M user equipment requires only a short message from the MSC, a combined attach or combined tracking area update request is sent to the MME, the message may include an indication of “SMS only”, and this indication depends on a preference of the M2M user equipment.
After the MME receives the message, the MME sends, according to an operator policy configured on the MME and/or subscription data of the user equipment (for example, there is only a short message service in CS domain subscription), the message to the HSS to request to be registered as a short message serving node. When a short message needs to be delivered, the HSS sends an address of the MME to the short message center, the short message center sends the short message to the MME, and the MME delivers the short message to the UE.
In the foregoing technical solution, the M2M user equipment may no longer obtain the short message from the MME in the following two situations: the preference of the M2M user equipment changes, for example, changes from “requiring only a short message service” to “not requiring the MME or MSC to provide a short message service”, which is specifically that the UE initiates only an independent attach or tracking area update process without requesting to be registered in the CS domain to obtain the short message service and the short message is transmitted by using an IP data packet when the UE registers with the MME; the operator policy on the MME changes, and an operator no longer requires the MME to provide the short message service.